restoration of the salton sea - six silberman · coordination with the state of california and the...

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U.S. Department of the InteriorBureau of ReclamationLower Colorado Region

Restoration of the Salton SeaSummary Report

September 2007

Mission Statements The mission of the Department of the Interior is to protect and provide access to our Nation’s natural and cultural heritage and honor our trust responsibilities to Indian Tribes and our commitments to island communities.

The mission of the Bureau of Reclamation is to manage, develop, and protect water and related resources in an environmentally and economically sound manner in the interest of the American public.

Restoration of the Salton Sea

Summary Report

U.S. Department of the Interior Bureau of Reclamation Lower Colorado Region Boulder City, Nevada September 2007

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Salton Sea location map.

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Abbreviations and Acronyms ALL Annualized Loss of Life

APF Annualized Probability of Failure

AQM air quality mitigation

BMPs best management practices

CEQA California Environmental Quality Act

CVWD Coachella Valley Water District

DEIS Draft Environmental Impact Statement

DO dissolved oxygen

DWR California Department of Water Resources

EIR Environmental Impact Report

EPA Environmental Protection Agency

ERS Ecosystem Restoration Studies

H2S hydrogen sulfide

IID Imperial Irrigation District

IMPLAN IMpact Analysis for PLANning

IPCC Intergovernmental Panel on Climate Change

LOL loss of life

m meters

µg/L micrograms per liter

maf/yr million acre-feet per year

mg/L milligrams per liter

msl mean sea level

NaCl halite

NED national economic development

NEPA National Environmental Policy Act

NH3 ammonia

NWR National Wildlife Refuge

OMER&R operation, maintenance, energy, replacement, and risk

Restoration of the Salton Sea Summary Report Abbreviations and Acronyms (continued)

P Phosphorus

P.L. Public Law

PEIR Programmatic Environmental Impact Report

P&Gs Principles and Guidelines

PHDA Progressive Habitat Development Alternative

PPG Reclamation’s Dam Safety Guidelines for Achieving Public Protection

QSA Quantification Settlement Agreement

Reclamation Bureau of Reclamation

RED regional economic development

Se selenium

Sea Salton Sea

SHC saline habitat complex

SSA Salton Sea Authority

SSAM Salton Sea Accounting Model

TMDL total maximum daily load

TSI trophic state index

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Contents Page

Abbreviations and Acronyms ................................................................... v

Executive Summary ................................................................................... xv

Chapter 1. Introduction............................................................................ 1-1

Purpose................................................................................................ 1-1

Authority............................................................................................. 1-1

Study Location.................................................................................... 1-1

Study Objectives ................................................................................. 1-2

History and Physical Setting of the Sea.............................................. 1-3

Important Resources ........................................................................... 1-4 Fishery........................................................................................ 1-4 Migratory Birds.......................................................................... 1-5 Recreation .................................................................................. 1-8 Endangered Species ................................................................... 1-9

Significant Problems and Challenges ................................................. 1-9 Salinity ....................................................................................... 1-10 Air Quality Concerns ................................................................. 1-10 Selenium .................................................................................... 1-11 Eutrophication............................................................................ 1-11

Responses to Comments on Draft Summary Report .......................... 1-12

Chapter 2. History of Plan Formulation................................................. 2-1

Chapter 3. Restoration Alternatives ....................................................... 3-1

Common Features ............................................................................... 3-2 Saline Habitat Complexes.......................................................... 3-2 Early Start Projects .................................................................... 3-3 Air Quality Mitigation Projects ................................................. 3-4

Alternative No. 1: Mid-Sea Dam with North Marine Lake (SSA Alternative) ...................................................................... 3-5

Alternative No. 2: Mid-Sea Barrier with South Marine Lake ........... 3-8

Alternative No. 3: Concentric Lakes (Imperial Group Alternative) ................................................................................ 3-10

Alternative No. 4: North-Sea Dam with Marine Lake....................... 3-12

Restoration of the Salton Sea Summary Report

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Alternative No. 5: Habitat Enhancement without Marine Lake ........ 3-14

Alternative No. 6: No-Project............................................................ 3-16

Embankment Design........................................................................... 3-18 Design Criteria and Considerations ........................................... 3-18 Evaluation of Embankment Designs.......................................... 3-20

Embankment Risk Analysis.............................................. 3-20 Sand Dam with Stone Columns Embankment Design ..... 3-21 Sand Dam without Stone Columns Embankment Design .......................................................................... 3-23 Habitat Pond Embankments Design ................................. 3-23 Geotube® Embankment Design ....................................... 3-23 SSA Rockfill Embankment Design .................................. 3-25

Comparisons to Design Criteria and Guidelines........................ 3-26

Chapter 4. Future Conditions .................................................................. 4-1

Water Supply Overview...................................................................... 4-1 Risk-Based Future Inflows ........................................................ 4-1 Total Future Inflows .................................................................. 4-2

Climate Change Effects on Evaporation............................................. 4-3

Assumptions Modeled Related to Project Completion....................... 4-4

Alternatives Modeling Results............................................................ 4-4 Water Surface Elevations........................................................... 4-4 Water Surface Areas .................................................................. 4-5 Salinities..................................................................................... 4-5 Exposed Lake Playa and Air Quality Mitigation Water

Requirements .................................................................... 4-5

Viability of Alternatives Relative to Future Inflows .......................... 4-7 Alternative No. 1: Mid-Sea Dam with North Marine Lake...... 4-8 Alternative No. 2: Mid-Sea Barrier with South Marine

Lake................................................................................... 4-9 Alternative No. 3: Concentric Lakes ........................................ 4-9 Alternative No. 4: North-Sea Dam with Marine Lake.............. 4-9 Alternative No. 5: Habitat Enhancement without

Marine Lake ...................................................................... 4-9 Alternative No. 6: No-Project ................................................... 4-10

Chapter 5. Biological Resource Issues .................................................... 5-1

Introduction......................................................................................... 5-1 Issues Overview......................................................................... 5-1 Objectives .................................................................................. 5-3

Assessment Methods........................................................................... 5-4 Area Determinations .................................................................. 5-5

Contents

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Selenium Concerns .................................................................... 5-6

Summary of Conditions under No-Project Alternative ...................... 5-7

Summary of Conditions under Restoration Alternatives.................... 5-9 Alternative No. 1: Mid-Sea Dam with North Marine Lake...... 5-11

Potential Benefits .............................................................. 5-11 Uncertainties ..................................................................... 5-11

Alternative No. 2: Mid-Sea Barrier with South Marine Lake................................................................................... 5-13 Potential Benefits .............................................................. 5-13 Uncertainties ..................................................................... 5-13

Alternative No. 3: Concentric Lakes ........................................ 5-13 Potential Benefits .............................................................. 5-13 Uncertainties ..................................................................... 5-13

Alternative No. 4: North-Sea Dam with Marine Lake.............. 5-13 Potential Benefits .............................................................. 5-13 Uncertainties ..................................................................... 5-14

Alternative No. 5: Habitat Enhancement without Marine Lake................................................................................... 5-14 Potential Benefits .............................................................. 5-14 Uncertainties ..................................................................... 5-14

Alternative No. 6: No-Project ................................................... 5-14

Alternative Assessment....................................................................... 5-14

Chapter 6. Environmental Factors Affecting Project Viability............ 6-1

Eutrophication..................................................................................... 6-2

Selenium ............................................................................................. 6-3

Fishery Sustainability ......................................................................... 6-7

Viability of Alternatives Relative to Environmental Factors ............ 6-9 Alternative No. 1: Mid-Sea Dam with North Marine Lake...... 6-10 Alternative No. 2: Mid-Sea Barrier with South Marine

Lake................................................................................... 6-11 Alternative No. 3: Concentric Lakes ........................................ 6-11 Alternative No. 4: North-Sea Dam with Marine Lake.............. 6-12 Alternative No. 5: Habitat Enhancement without Marine

Lake................................................................................... 6-12 Alternative No. 6: No-Project ................................................... 6-12

Chapter 7. Costs of Alternatives.............................................................. 7-1

Total Project Implementation Costs ................................................... 7-3

Annual Operation, Maintenance, Energy, Replacement, and Risk Costs .......................................................................................... 7-5

Summary of Restoration and Air Quality Mitigation Costs ............... 7-6


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Chapter 8. Economic Analyses ................................................................ 8-1

Conceptual Overview ......................................................................... 8-1

National Economic Development (NED) Costs ................................. 8-2

NED Benefits...................................................................................... 8-2

Recreation Benefits............................................................................. 8-3

Nonuse Environmental Benefits ......................................................... 8-4

Cost Effectiveness and Risk ............................................................... 8-5

Regional Economic Development (RED)........................................... 8-7

RED Results........................................................................................ 8-9

Chapter 9. Restoration Study Findings and Recommendations .......... 9-1

Risks to Alternatives........................................................................... 9-1 Alternative No. 1: Mid-Sea Dam with North Marine Lake...... 9-1 Alternative No. 2: Mid-Sea Barrier with South Marine

Lake................................................................................... 9-2 Alternative No. 3: Concentric Lakes ........................................ 9-2 Alternative No. 4: North-Sea Dam with Marine Lake.............. 9-2 Alternative No. 5: Habitat Enhancement without Marine

Lake................................................................................... 9-3

Discussion of Cost of Alternatives ..................................................... 9-3

Cost Effectiveness and Risk ............................................................... 9-3

Recommendations for the Future........................................................ 9-4

References ................................................................................................... Ref-1

Attachment A – Cost of Alternatives Using Embankment Designs that do not Meet Reclamation Design Criteria and Guidelines............. A-1

Attachment B – Response to Comments .................................................. B-1

Contents

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Figures Salton Sea location map............................................................................... iii Figure 1.1 Historic Earthquakes Magnitude 3 to 8 ............................... 1-3 Figure 1.2 Flyways for migratory birds................................................. 1-6 Figure 1.3 Recovered and encountered birds banded at the Salton Sea 1-7 Figure 3.1 Cell in a typical SHC ........................................................... 3-3 Figure 3.2 Alternative No. 1: Mid-Sea Dam with North Marine

Lake (SSA Alternative)..................................................... 3-6 Figure 3.3 Alternative No. 2: Mid-Sea Barrier with South

Marine Lake ...................................................................... 3-8 Figure 3.4 Alternative No. 3: Concentric Lakes .................................. 3-10 Figure 3.5 Alternative No. 4: North-Sea Dam with Marine Lake........ 3-12 Figure 3.6 Alternative No. 5: Habitat Enhancement without

Marine Lake ...................................................................... 3-15 Figure 3.7 Alternative 6: No-Project.................................................... 3-16 Figure 3.8 Typical cross-section of sand dam with stone columns....... 3-22 Figure 3.9 Typical cross-section of habitat embankment...................... 3-24 Figure 3.10 Typical Geotube® design. ................................................... 3-25 Figure 3.11 Typical cross-section of the SSA rockfill

embankment...................................................................... 3-25 Figure 4.1 Risk-based possibility distribution of total inflows from all

sources............................................................................... 4-3 Figure 4.2 Mean future water surface elevations for restoration

alternatives ........................................................................ 4-5 Figure 4.3 Mean future water surface areas for restoration

alternatives ........................................................................ 4-6 Figure 4.4 Mean future salinity for restoration alternatives.................. 4-6 Figure 8.1 Cost effectiveness (NED present worth costs per acre of

shoreline and open water habitat created in year 2040).... 8-6 Figure 9.1 Progressive Habitat Development Alternative

Conceptual Diagram ......................................................... 9-8


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Tables Table 3.1 Physical features of Alternative No. 1: Mid-Sea Dam

with North Marine Lake....................................................... 3-6 Table 3.2 Physical features of Alternative No. 2: Mid-Sea Barrier

with South Marine Lake....................................................... 3-9 Table 3.3 Physical features of Alternative No. 3: Concentric Lakes....... 3-11 Table 3.4 Physical features of Alternative No. 4: North-Sea Dam

with Marine Lake................................................................. 3-12 Table 3.5 Physical features of Alternative No. 5: Habitat Enhancement

without Marine Lake............................................................ 3-14 Table 3.6 Physical features of Alternative No. 6: No-Project .................. 3-17 Table 3.7 Salton Sea Restoration Study: Embankment/Alternative

Comparisons to Reclamation’s Design Criteria and Guidelines ..................................................................... 3-27

Table 4.1 Exposed lake playa surface areas............................................... 4-7 Table 5.1 Avifauna functional groupings associated with various

habitat types present within and/or adjacent to the Salton Sea................................................................... 5-2

Table 5.2 Summary comparison of shoreline habitat, open water habitat, and food provided under restoration alternatives and No-Project Alternative in the year 2040.............................................................................. 5-12

Table 6.1. Calculated TSI for Salton Sea alternatives ................................ 6-4 Table 6.2 Selenium effect levels ................................................................ 6-5 Table 6.3 Alternative viability assessment summary................................. 6-10 Table 7.1 Alternatives and Associated Component Construction

Costs..................................................................................... 7-2 Table 7.2 Summary of annual re-occurring costs of restoration

alternatives ........................................................................... 7-3 Table 7.3 Summary of Restoration and Air Quality Mitigation

Project Implementation and OMER&R Costs .................... 7-7 Table 8.1 NED costs of alternatives, present worth basis,

expressed in 2006 millions of dollars using 5.125% discount rate............................................................ 8-3

Table 8.2 Regional economic impacts from construction of each alternative, incremental to No-Project Alternative, compared to the economy of Imperial and Riverside Counties ............................................................................... 8-9

Table 9.1 Summary of Progressive Habitat Development Alternative and AQM project implementation and OME&R costs...................................................................... 9-7

Contents

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Table A-1 Alternatives and Associated Component Subtotal Construction Costs and Implementation Costs for Alternatives with Embankment Designs that Do Not Meet Reclamation Design Criteria and Guidelines ............................................................................ A-1

Table A-2 Summary of Annual Reoccurring Costs of Restoration Alternatives($ million) for Alternatives with Embankment Designs that Do Not Meet Reclamation Design Criteria and Guidelines....................... A-2

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Executive Summary This report provides a summary of the Bureau of Reclamation’s (Reclamation) recent study to determine a preferred alternative action for restoring the Salton Sea (Sea). The study was performed in fulfillment of the requirements of Public Law (P.L.) 108-361, the Water Supply Reliability and Environmental Improvement Act, November 2004 which states:

“Not later than December 31, 2006, the Secretary of the Interior, in coordination with the State of California and the Salton Sea Authority, shall complete a feasibility study on a preferred alternative for Salton Sea restoration.”

The costs of all alternatives presented in this report are based on very limited geologic and geotechnical data that were obtained through exploration in years 2003 and 2004. Significant design uncertainties exist as a result of the limited amount of site information. Uncertainties also exist relative to constructability, seismic performance, static performance, and construction costs. As a result of these uncertainties, the designs and costs presented in this report are at an appraisal level and not at a feasibility level. It would not be possible to develop feasibility level designs and cost estimates without conducting significant geologic and geotechnical design data collection programs.

Study Objectives

The objective of this study is to identify and recommend a preferred action that attempts to provide an efficient and reasonable method for restoration of the Salton Sea ecosystem and permanent protection of wildlife dependent on that ecosystem. This objective is based on historic habitat capabilities for providing an abundant and diverse assemblage of fish and wildlife at a level sustainable: (1) within the constraints of predicted future water availability and water quality; (2) at a reasonable degree of risk associated with the viability of the project (relative to environmental issues); and (3) in a cost-effective manner. Although wildlife and wildlife habitat objectives were primary considerations for this study, all objectives listed in the Salton Sea Reclamation Act (P.L. 105-372) were given significant consideration and addressed to the greatest extent possible.

Emphasis was given to permitting the continued use of the Salton Sea for irrigation drainage and for reclaiming fish and wildlife resources and their habitats. An additional objective was considered relative to minimizing exposed areas subject to potential air quality problems. This additional objective was not included in the Salton Sea Reclamation Act. It was added for this study because


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of its importance to restoration feasibility and for consistency with the State of California’s Salton Sea Ecosystem Restoration Study (ERS).

Project features are designed in this study to function at current and reduced inflows, as directed by P.L. 105-372 (the Salton Sea Reclamation Act of 1998).

Restoration Study Findings and Recommendations

This report recommends a potential action for consideration at the Salton Sea that attempts to provide an efficient and reasonable method for restoration of the Salton Sea ecosystem and permanent protection of wildlife dependent on that ecosystem. The recommendation takes into consideration the best available (but still limited) information as well as estimated risks, costs, and predicted outcomes. All five action alternatives considered in this report entail extreme costs and there are substantial uncertainties and risks associated with engineering, physical, and biological elements of the alternatives. These risks are directly associated with a lack of data and/or uncertainty involving the description, implementation, and subsequent performance of each of the proposed alternatives. The following risks were considered in the evaluation of alternatives:

• Selenium risks to fish-eating birds • Selenium risks to invertebrate-eating birds • Hydrodynamic/stratification risks • Eutrophication risks • Fishery sustainability risks • Future inflow risks

While lack of data and the time and funding required to analyze these data did not allow a full feasibility level study, a more detailed evaluation would not resolve the hydrologic and biologic uncertainties. Therefore, Reclamation does not have a basis for recommending implementation of any of the action alternatives evaluated in this report. At an appraisal level of evaluation, all of the action alternatives considered in this report have been estimated to cost between $3.5 and $14 billion (Table ES.1). Annual costs associated with the alternatives are also very high. Estimated annual operations, maintenance, energy, and replacement costs for all the alternatives range from $119 million to $235 million (Table ES.2); and again, there are many risks and uncertainties associated with these estimates. However, given the degree of negative air quality impacts and related mitigation cost ($1.4 billion)1 associated with the No-Project Alternative,

1 An estimated dollar amount of $1.4 billion would be required to mitigate air quality impacts

associated with the No-Project Alterative due to reduced inflows and resulting exposed lakebed sediments becoming emissive. Over time, approximately 92,000 acres of exposed sediments could be exposed and potentially become emissive under the No-Project Alternative. Mitigation

Executive Summary

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consideration could be given to a focused adaptive management study of shallow saline habitat complexes (habitat complexes as describe in Alternative 5). Current data indicate that these types of habitat complexes could minimize both risk and costs, while providing historic wildlife habitat replacement and partial mitigation of air quality impacts associated with reduced future inflows at the Salton Sea. Although there are presently many remaining unknowns, risks and uncertainties concerning these habitat complexes,2 the development and study of approximately 2,000 acres of such habitat, over a 7- to 10-year period, could determine if these complexes are a feasible approach to replacing historic wildlife use values at the Sea.

While Reclamation does not support the recommendation of any preferred action alternative at this time, a focused and progressive adaptive management study initiative of saline habitat complexes could be undertaken to determine if such complexes are a feasible approach to replacing historic wildlife use values at the Sea. This concept could involve developing, studying, and monitoring relative small parcels of habitat in a phased approach of shallow saline habitat complexes (SHC) in an adaptive and flexible, yet progressive, manner. This concept could be described as a Progressive Habitat Development Alternative (PHDA).3

Each phase would include construction of between 200 and 500 acres of saline habitat complex (SHC), in which engineering designs and wildlife management criteria and strategies could be derived from a previous phase. During each phase, continuous detailed evaluations could be obtained concerning water quality, habitat values and use, biologic issues, and engineering performance. Information from these evaluations would be used to refine the designs and adaptive strategies for the next phase of complexes. Development of adaptive and flexible strategies would reduce risks and uncertainties associated with operating larger complexes. Actual habitat values would be determined through continuous observations and study.

Initial design of management strategies for the first phase would be based on what is being learned at the existing 100-acre shallow habitat pilot project currently being studied cooperatively by the United States Geological Survey and Reclamation. The goals of this study are to begin assessing the benefits of shallow water wetlands to breeding birds, and also to study potential risks due to contamination from agricultural drain water. Focus is being given to evaluating

of these potentially emissive sediments is estimated to cost about $14,000 per acre and would ultimately be the responsibility of the existing landowner to mitigate.

2 Of particular concern is the lack of species-specific values that these habitat types may provide and the uncertainty as to whether other Pacific Flyway problems might affect values derived from habitat areas developed at the Salton Sea. Estimates of bird densities that might be achievable, based on what is known today, may not be possible in the future.

3 A PHDA feasibility study is estimated to involve approximately 2,000 acres, to be developed in phases over approximately 7 to 10 years, and to cost approximately $150 million (implementation) and $50 million in annual operation and maintenance.


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post-hatchling survival and movement of birds nesting on the 100-acre site. Preliminary and non-peer-reviewed information from the 100-acre project indicates instances of wetland usage by large numbers of birds of multiple species.

It is recommended that PHDA would be implemented by committing to an initial 2,000 acres during the first 7 to 10 years, assuming phased construction of 300 acres per year. PHDA habitat areas could continue to be added beyond those constructed in the first 7 to 10 years up to what is determined to be historic values at the Sea. The maximum buildout of habitat acreage (beyond the initial 2,000 acres) would be dependent on what actual habitat values were derived from observation and study of previous phases and upon the success of developing adaptive and flexible strategies for managing and/or mitigating observed problems, risks, and uncertainties. All risks could not, however, be alleviated by the PHDA approach. There could be no guarantee that habitat values would be sustainable. Pacific Flyway impacts from actions and events occurring outside of the Salton Sea area could have a significant impact on bird densities and habitat values derived from SHC areas at the Salton Sea. Figure ES.1 is a diagram displaying an example of a successional construction strategy of SHC, with each phase using lessons learned from previous phases of development.

PHDA could also allow for studying adaptations of embankment and water conveyance designs and construction methods with the purpose of determining the most cost-effective methods for constructing SHC areas. Each phase of design and construction would rely on lessons learned from previous phases.

The PHDA concept would need to be refined based on information being collected at the existing 100-acre complex in order to determine an accurate cost estimate for a phased project of 2,000 acres and beyond. However, the appraisal level cost of implementing projects of different sizes can be estimated on the basis of appraisal level estimates that have been compiled for SHC incorporated in alternatives evaluated for this study. Estimated PHDA implementation costs (in 2006 dollars) for the 2,000 acres are $150 million. Estimated PHDA annual operation, maintenance, energy and replacement costs would be $600,000 per year once the 2,000 acres were completed.

Restoration Alternatives

This present study of alternative concepts for restoring the Salton Sea uses information from both recent and past studies (1960s to present). The specific concepts evaluated in this present study were screened and selected from hundreds of ideas and concepts that ranged from circulating ocean water from the Gulf of California or the Pacific Ocean to removing salts at the Sea through the use of enormous desalination plants, solar pond systems, and/or enhanced evaporation systems. As a result of anticipated reduced future inflows (from

Executive Summary

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Figure ES.1 Progressive Habitat Development Alternative Conceptual Diagram.


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implementation of the Imperial Irrigation District and San Diego Water Transfer Project), alternatives involving salt removal and disposal were abandoned in favor of partial restoration solutions such as equal head barriers and impervious dam alternatives as well as habitat-pond-based alternative concepts. Reclamation’s current alternatives include only these types of alternatives. The current alternatives presented in this summary report are as follows:

1. Mid-Sea Dam with North Marine Lake (proposed by the Salton Sea Authority [SSA])

2. Mid-Sea Barrier with South Marine Lake

3. Concentric Lakes (proposed by the Imperial Group)

4. North-Sea Dam with Marine Lake

5. Habitat Enhancement without Marine Lake

6. No-Project

Reclamation coordinated closely with the State of California Department of Water Resources and the Salton Sea Authority in developing the alternatives presented in this report. Consequently, both the State and Reclamation have analyzed alternatives that are conceptually similar, yet have some differences. Variation between agencies in approaches to risk, uncertainty, complexity, and other factors contribute to differences in designs and costs. While Reclamation’s design and cost estimating criteria and guidelines may be different than those used by other agencies and this may lead to different design conclusions and project costs, Reclamation makes no judgment relative to methods, assumptions, and criteria used by others.

Costs of Alternatives

Table ES.1 displays appraisal level estimates of subtotal construction and implementation costs of all alternatives, including the No-Project Alternative, using embankment designs that meet Reclamation’s design criteria and guidelines. Table ES.2 presents appraisal level annual recurring costs of all the alternatives. All appraisal level cost estimates are expressed in 2006 price levels for comparison purposes.

Total implementation costs for the action alternatives vary from a minimum of $3.5 billion to a maximum of $14.0 billion. The cost of the No-Project is estimated at $1.4 billion which is merely the estimated cost associated with AQM. Annual reoccurring costs for the action alternatives vary from a minimum of $119 million to a maximum of $235 million. The annual reoccurring costs for the No-Project Alternative are estimated at $164 million, again solely associated with AQM efforts.

Executive Summary

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Table ES.2 Summary of annual re-occurring costs of restoration alternatives ($ million)

Alternative

Annual Operations,

Maintenance, and Energy

(OM&E) Costs

Annual Replacement

Costs

Annual Operations,

Maintenance, Energy, and Replacement

(OME&R) Costs

Annual Risk

Costs 2

Annual Operations, Maintenance,

Energy, Replacement, and Risk

(OMER&R) Costs

Alternative No. 1A: Mid-Sea Dam with North Marine Lake using Sand Dam Design with Stone Columns

148 87 235 5 240

Alternative No. 2A: Mid-Sea Barrier with South Marine Lake using Sand Dam Design with Stone Columns

71 62 133 3 136

Alternative No. 3A: Concentric Lakes using Sand Dam Design with Stone Columns 1

64 55 119 1 120

Alternative No. 4: North-Sea Dam with Marine Lake using Sand Dam Design with Stone Columns

89 77 166 6 172

Alternative No. 5: Habitat Enhancement without Marine Lake

79 68 147 7 154

Alternative No. 6: No-Project 87 77 164 0 164

1 Costs shown are for three concentric lakes as required under mean possible future inflow conditions. 2 Risk costs are defined as the annualized cost of repairing structures calculated from estimated annualized probabilities of failure (from major seismic events) and from estimates of how much of a structure would have to be repaired as a result of the failure.

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Chapter 1. Introduction

Purpose

This report is intended to provide a summary of the Bureau of Reclamation’s (Reclamation) recent study to determine a preferred alternative action for restoring the Salton Sea (Sea). This study was performed in fulfillment of the requirements of Public Law (P.L.) 108-361, the Water Supply Reliability and Environmental Improvement Act, November 2004.

Authority

This study is being conducted under the authority of P.L. 108-361, titled the Water Supply Reliability and Environmental Improvement Act. Specifically, the act requires that:

“Not later than December 31, 2006, the Secretary of the Interior, in coordination with the State of California and the Salton Sea Authority, shall complete a feasibility study on a preferred alternative for Salton Sea restoration.”

The costs of all alternatives presented in this report are based on very limited geologic and geotechnical data that were obtained through exploration in years 2003 and 2004. Significant design uncertainties exist as a result of the limited amount of site information. Uncertainties also exist relative to constructability, seismic performance, static performance, and construction costs. As a result of these uncertainties, the designs and costs presented in this report are at an appraisal level and not at a feasibility level. It would not be possible to develop feasibility level designs and cost estimates without conducting significant geologic and geotechnical design data collection programs.

Study Location

The Sea, a terminal hypersaline lake, is the largest inland body of water in California. It is located in the southeastern corner of the State and spans Riverside and Imperial Counties (location map). The closest cities include Palm Springs, Indio, Brawley, and El Centro.

The northern portion of the study area is drained by the Whitewater River and its tributaries, reaching the northern end of the Salton Sea within the Coachella Valley not far from the town of Mecca. Salt Creek drains the southern slope of the Orocopia Mountains and the northern end of the Chocolate Mountains,


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entering the northeast portion of the Sea within the Salton Sea State Park boundaries. The most important western drainage is San Felipe Creek, with headwaters near Julian, about 50 miles west of the Salton Sea. The New and Alamo Rivers drain the Imperial Valley and, to a lesser extent, the Mexicali Valley to the south.

Study Objectives

The primary purpose of this study is to identify and recommend a preferred action that attempts to provide an efficient and reasonable method for restoration of the Salton Sea ecosystem and permanent protection of wildlife dependent on that ecosystem. This objective is based on historic habitat capabilities for providing an abundant and diverse assemblage of fish and wildlife at a level sustainable (1) within the constraints of predicted future water availability and water quality, (2) at a reasonable degree of risk associated with the viability of the project (relative to environmental issues), and (3) in a cost effective manner. Although wildlife and wildlife habitat objectives were considered primary for this study, all objectives listed in the Salton Sea Reclamation Act (P.L. 105-372) were given significant consideration and adopted to the greatest extent possible. P.L. 105-372 identified the following objectives:

• Permit the continued use of the Salton Sea as a reservoir for irrigation drainage

• Reduce and stabilize the overall salinity of the Salton Sea

• Stabilize the surface elevation of the Salton Sea

• Reclaim, in the long term, healthy fish and wildlife resources and their habitats

• Enhance the potential for recreational uses and economic development of the Salton Sea

Emphasis was given to permitting the continued use of the Salton Sea for irrigation drainage and for reclaiming fish and wildlife resources and their habitats. An additional objective was considered relative to minimizing exposed areas subject to potential air quality problems. This additional objective was not included in the Salton Sea Reclamation Act. It was added for this study because of its importance to restoration feasibility and for consistency with the State of California’s Salton Sea Ecosystem Restoration Study (ERS).

Project features are designed in this study to function at current and reduced inflows, as directed by P.L. 105-372.


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History and Physical Setting of the Sea

The Salton Sea lies at the northern reach of the former delta of the Colorado River (Sykes, 1937) in a large, seismically-active rift valley that was once the northernmost extent of the Gulf of California. Before 1900, the river periodically emptied northwest into the Salton Basin, forming the ancient Lake Cahuilla, which was several times the size of the current Sea. The present-day Sea formed in 1905, when Colorado River flood flows breached an irrigation control structure in Mexico and were diverted into the Salton Basin for about 18 months. Since then, agricultural drainage flows from nearby Imperial, Coachella, and Mexicali Valleys and smaller contributions from municipal effluent and storm water runoff have sustained the Sea.

The present-day Salton Sea occupies a below-sea-level desert basin known as the Salton Basin (or Salton Sink or Salton Trough). The Salton Basin is located in a highly active tectonic region with frequent earthquakes. Tectonically, the vicinity is dominated by the San Andreas, Imperial, San Jacinto, and Elsinore fault systems. Many moderate-to-large earthquakes have occurred on faults in the Salton Basin. Figure 1.1 displays historic earthquakes in the Salton Basin from the 1860s through the year 2005.4

Figure 1.1 Historic Earthquakes Magnitude 3 to 8.

1 This map was obtained from Reclamation’s Western United States Earthquake Database.


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The Salton Basin extends from Banning, California, on the north to near the international border of Mexico on the south. The Sea itself is about 35 miles long and 15 miles wide. Recently, the elevation of the Sea has been about -228 feet mean sea level (msl) (228 feet below sea level), with annual fluctuations of about 1 foot. At this elevation, the Sea has a maximum depth of about 50 feet, with an estimated surface area of 232,000 acres (362 square miles). The lowest Seafloor elevation is about -278 feet msl. The current Sea has a storage volume of approximately 7.2 million acre-feet.

The Sea’s recent salinity concentration (48,000 milligrams per liter [mg/L]) is about 37 percent saltier than ocean water. In the recent past, annual inflows to the Sea have been in balance with its annual evaporation. Inflows add about 4 million tons of salt each year. Because the Sea has no natural outlet, the salinity in the Sea continues to rise each year as salts (or total dissolved solids) are left behind when water evaporates from the Sea surface. Salton Sea salinity will increase dramatically in the near future as inflows to the Sea are reduced due to implementation of existing water transfer agreements. This accelerated increase will occur because of an imbalance between inflow and evaporation. Rising salinities have affected, and are expected to continue to affect, the once highly productive fishery of the Sea.

Important Resources

Fishery The fishery of the Salton Sea is an important (but declining) resource for both fish-eating birds and the local economy through recreational sport fishing. Beginning in 1929, the California Department of Fish and Game introduced more than 30 marine fish species to the Salton Sea. Only three of those species, sargo (Anisotremus davidsoni), Gulf croaker (Bairdiella icistia), and orangemouth corvina (Cynoscion xanthulus), adapted and became established. A fourth species, tilapia (Oreochromis mossambicus x O. urolepis hornurum), was unintentionally introduced to the Sea from agricultural drains in 1964-65. By the early 1970s, tilapia dominated the fish community in the Sea. Extensive surveys in 1999–2000 (Reidel et al., 2002) indicated that growth rates of tilapia in the Salton Sea were among the highest reported anywhere in the world as a result of the high nutrient concentrations and warm temperatures. In addition to the game fish, the endangered desert pupfish (Cyrinodon macularius) inhabits the Sea and adjoining drains and creeks and is of concern with respect to restoration alternatives.

Increasing salinity and dissolved oxygen (DO) levels currently pose the greatest threat to the Salton Sea fishery, although temperature fluctuations may become of concern as water levels drop. Reidel et al. (2002) reported that the optimum salinity range for food consumption and conversion, growth, and respiration for sargo, croaker, and orangemouth corvina was 33-37 grams per liter. Furthermore,


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current salinities in the Sea appear to be nearing the upper tolerance limits for all four of major species. In fact, recent increases in salinity may have already impaired the Salton Sea fishery. Crayon et al. (2005) recently reported that populations of sargo, Gulf croaker, and orangemouth corvina have been below detectable levels since May 2003. Tilapia populations have also been drastically reduced. Although tilapia numbers appear to be increasing, current populations are still more than 90 percent lower than the levels reported in 1999–2000.

Migratory Birds The seasonal movements of migratory species of birds follow general, but complex, pathways that take birds from their breeding grounds to wintering areas and, subsequently, back to these breeding grounds. That journey must be supported by the availability of appropriate habitat and an adequate food base. Those essential factors must be satisfied within the limits of flight and bioenergetic considerations to provide for the return of sufficient numbers of birds in a physical condition that facilitates long-term population maintenance. The Pacific Flyway is an important migratory pathway for birds traveling between the breeding grounds in Canada, Alaska, the Pacific Northwest, and the Northern Great Plains and wintering grounds along the Gulf of California, extending into Central and South America (Figure 1.2).

The Salton Sea is an important link in the habitat and food chain that sustains the perpetual migratory cycles for many species of birds within Western North America. This linkage is that of a habitat for all seasons by providing an important crossroad and way station for seasonal resting and feeding needs, wintering, spring conditioning, and breeding habitat. Records of the U.S. Geological Survey’s Bird Banding Laboratory disclose that birds banded at the Salton Sea have been reported from Russia and the North American Arctic to Latin America and from Hawaii to the Maritime Provinces of Eastern Canada (Figure 1.3). The considerable interchange evident with birds of the Pacific and Central Flyways indicates that the importance of the Sea is far greater than transient local and regional bird use.

The Salton Sea ecosystem supports some of the highest avian biological diversity in North America as well as the world. The more than 400 bird species that have been reported within the Salton Sea ecosystem comprise approximately 70 percent of all the bird species recorded in California. In addition, approximately 100 species, or one-third of all species that are known to breed in California, are breeders

Wood Storks


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Figure 1.2 Flyways for migratory birds.


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Figure 1.3 Recovered and encountered birds banded at the Salton Sea.

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within the Salton Sea ecosystem. This combination of avian biodiversity and importance as breeding habitat is unsurpassed by any limited geographic area within the contiguous 48 states and Latin America.

Among the birds using the Salton Sea are 19 species of waterbirds classified by the Federal government, California, or both, as species of high conservation concern because of their population status. More than 14,000 pairs of colonial breeders, comprised of 11 species representing three families of birds, were tallied during a 1999 survey (Shuford et al., 2000).

The Salton Sea ecosystem is also an important area for landbirds. Investigators from the Point Reyes Bird Observatory during surveys in 1999 in areas adjacent to the Salton Sea tallied numerous neotropical migrants. More Wilson’s warblers (Wilsonia pusilla) were caught at the Salton Sea during spring migration than at any other mist-netting site in California. The abundance of neotropical migrants recorded during spring and fall included 11 species of statewide concern in riparian habitats and is evidence that the area is used extensively by migrating passerines (Shuford et al., 2000).

In general, the Salton Sea is of regional or national importance to various groups of birds such as pelicans and cormorants, wading birds, waterfowl, shorebirds, gulls and terns, and some passerines. The Salton Sea ecosystem is a migratory bird habitat for all seasons that serves waterbirds and landbirds alike.

Recreation Soon after its creation, the Salton Sea became a mecca for outdoor recreation. By 1958, the North Shore Beach area had been developed with an airfield and a yacht club. The North Shore Yacht Club was touted as a $2 million marine paradise, with one of the largest marinas in Southern California. The development of Salton City also began in earnest during the 1950s on the west side of the Salton Sea.

The development included a championship golf course and the Salton Bay Yacht Club, both of which were frequented by Southern California sportsmen and Hollywood celebrities. Developers claimed that Salton City would become the most popular marine resort in all of Southern California. The Salton Sea State Park (later the Salton Sea State Recreation Area) was dedicated on February 12, 1955. It served as an important inland recreation area until the late 1970s when visitation declined markedly because of the deteriorating environmental quality of the Sea. This facility has 1,400 campsites, hundreds of day use sites, and other amenities. Current annual visitor use at the park is about 250,000 people.

Waterfowl hunting has been a popular activity at the Salton Sea since at least the 1920s. There are numerous private duck clubs along the Sea and on adjacent areas. Hunters are also provided waterfowl opportunities on portions of the


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Sonny Bono Salton Sea National Wildlife Refuge (NWR) and on the State’s Imperial Wildlife Area Wister Unit.

The annual Salton Sea International Bird Festival attests to the popularity of the Salton Sea ecosystem as a haven for bird watching. An earlier economic analysis of bird watching at the Salton Sea reported substantial contributions to the economy of the small local communities around the Salton Sea.

A variety of other recreational activities also take place at the Salton Sea, including photography, camping, and kayaking. Because of its relative proximity to the large metropolitan areas of San Diego and Los Angeles, the Salton Sea is a valuable recreation resource.

Endangered Species Several species listed under the Federal Endangered Species Act use habitat resources associated with the Salton Sea; however, four species are directly linked to future changes in Salton Sea water quantity and quality. For example, the desert pupfish is the only native fish inhabiting the Salton Sea. Designated critical habitat includes San Felipe Creek, Carrizo Wash, and Fish Creek Wash; however, pupfish also occur in wastewater drains discharging into the Sea, in shoreline pools of the Sea, artificial refugia, and in washes at San Felipe and Salt Creeks (Sutton, 2000). There is some indication that pupfish may use the Sea to move between sites providing habitat resources. As the Sea becomes more saline and the shoreline recedes in the future, there is concern that local pupfish populations may become isolated as they loose habitat connectivity with adjacent populations. All alternatives contain some provisions to maintain connectivity among local pupfish populations.

Two listed bird species may also be affected by future changes in the Sea. Brown pelicans use the Sea for feeding, nesting, and roosting. As the Sea becomes more saline and the shoreline recedes in the future, fish will disappear and the small islands used by pelicans will become connected to shore—thus loosing their security value. There are also concerns of selenium (Se) bioaccumulation in food chains used by fish-eating birds such as pelicans. Yuma clapper rails use freshwater marshes managed as wildlife habitat at the south end of the Sea, and some brackish sites associated with wastewater drains and river deltas. These brackish areas will likely disappear as the Sea becomes more saline and the shoreline recedes. There is also concern of Se bioaccumulation in food chains used by invertebrate-eating birds such as rails as Se concentrations in wastewater increase.

Significant Problems and Challenges

Among the problems and challenges facing the Salton Sea are increasing salinity, air quality concerns, Se, and eutrophication, as discussed in this section.


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Salinity Salinity is the more time-sensitive problem and must be dealt with so that the Sea survives long enough for the other, more complex problems to be addressed. This is not an either/or situation, as the investment in controlling salinity will be lost if the other problems are not also addressed.

As noted previously, the Sea has salinity measured recently at about 48,000 mg/L. In the absence of more definitive current information, at a salinity of 60,000 mg/L, the majority of the fishery is projected to be lost. Historically, the fishery supported species with differing levels of tolerance to salinity. In recent years, the sport fishery has declined dramatically. Sargo, croaker, and orangemouth corvina currently are not being detected in gill net samplings. Tilapia currently are rebounding from dramatic reductions that occurred over the last few years. It has been predicted that some age classes and species would likely to be lost at lower levels of salinity, thereby initiating a general decline in the fishery several years before a salinity of 60,000 mg/L is reached. This could be what has been occurring over the last few years.

The impacts of salinity on invertebrate populations also have significant biological ramifications. The pileworm (Neanthes succinea) is a major food source for some species of fish and birds. As salinity increases, a time will occur in the near future when pileworms will no longer be present in this ecosystem. Other invertebrates, such as brine flies (Ephybra spp.), will be favored by increased salinity. The shift in invertebrate populations will be beneficial for a few species of birds, but not for many others.

Air Quality Concerns Winds in the Salton Sea basin generate large dust storms. As the Sea recedes in the future, there could be as much as 140 square miles of lake bed (“playa”) exposed that could significantly increase fugitive dust in the basin. Human health is a concern related to these potential increases. Particles with a diameter of less than 10 microns (PM10) are of primary concern. The Imperial Valley already suffers from the highest childhood asthma rate in the State. Furthermore, elderly people are especially susceptible to poor air quality (Cohen, 2006).

Sediment moisture, salt and sediment composition, and the extent of vegetation establishment all have major influences on the susceptibility of exposed sediments to wind erosion. Active disturbance of any exposed sediments can significantly increase the potential for wind erosion. Many major reservoirs experience significant seasonal changes in water elevation without generating serious fugitive dust problems during periods of low water levels. But serious fugitive dust problems have developed at two alkaline lakes in California—Owens Lake and Mono Lake. It is not known to what extent the Salton Sea will contribute to dust emissions, but it is assumed there is a risk that exposed playa areas would be emissive. Potential air quality mitigation projects are discussed in Chapter 3.


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Selenium Se is a naturally occurring semi-metallic trace element with biochemical properties similar to sulfur, and it is an essential trace nutrient necessary for normal metabolic functions. However, there is a narrow margin between nutritionally optimal and potentially toxic dietary exposure concentrations of Se for vertebrates. Effects of Se toxicity can range from hair/feather loss to death. Reproductive impairment—a common concern in Se studies—is exposure responsive, meaning the higher the concentration, the greater the effect. Se is a consideration in Salton Sea studies because of the potential for bioaccumulation in aquatic food chains supporting abundant and diverse bird use of the area. Bioaccumulation can occur when Se is acquired from one level of a food chain and passed on to the next higher level. For example, Se can be accumulated from water and/or sediments by bacteria and algae and passed on to macro-invertebrates that feed on them. Birds that feed on the macro-invertebrates would then accumulate larger amounts of Se. Under certain conditions, Se can accumulate to toxic levels in food chains (e.g., in birds).

Se cycling involves the interaction of physical, chemical, and biological components of aquatic systems. The processes and interactions are complex and can possess system unique characteristics. For example, Se concentrations in drainage water entering the Salton Sea are at levels that would normally cause concern for bioaccumulation within the Sea’s food chains. However, the interaction of system components currently characterizing the Sea results in a sequestering of Se in bottom sediments. Se levels available for accumulation in food-chains originating in the Sea are, therefore, lower than would be expected from a different blend of system components. Se concerns for the Salton Sea focus on the uncertainties associated with the interactions of the physical, chemical, and biological components that would characterize the future under the No-Project Alternative and/or the future under the restoration alternatives. The future Salton Sea system may support Se cycling similar to the current situation, or a different system—with different Se risk to local food chains—may be supported.

Eutrophication Eutrophication is the enrichment of lakes by nutrients, typically nitrogen and phosphorus (P). High concentrations of nutrients can lead to increased growth of algae and aquatic plants and decreased species diversity. Eutrophication is a natural aging process in some lakes, but it is frequently accelerated by nutrient loadings arising from human activity.

Nutrient loadings to the Salton Sea are very high because of the variety of both nonpoint sources (primarily agricultural runoff) and point sources (wastewater treatment plant effluent) of nutrients in the watershed. As a result, the Sea is classified as hypereutrophic, a term used for lakes with the highest nutrient and chlorophyll a concentrations and the lowest transparency. In hypereutrophic lakes, algae and other organic matter decompose, creating severe oxygen


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depletion. Oxygen depletion at the Salton Sea has caused fish kills and has contributed to other chemical changes that create odors and other nuisance conditions.

The size of the Sea would be reduced under the various alternatives, which could result in intense and persistent thermal stratification at depths greater than 10 meters (m) (33 feet). (Thermal stratification refers to the layering that occurs, particularly in the warmer months, when a warmer, less dense layer of water [the epilimnion] overlies a colder, denser layer [the hypolimnion]). As a result, the Sea would switch from a system with several mixing events per year, to a system that is mixed for a relatively brief period in the winter. This stability and the expected continuing eutrophication would make the hypolimnium of the Sea anoxic (i.e., contain no DO) for most of the year.

With this extensive anoxia, hydrogen sulfide (H2S) and ammonia (NH3) could build up to unprecedented levels because of the lack of mixing. When the Sea does mix, the rapid breakdown of the stratification could potentially lead to a sudden redistribution of anoxia, H2S, and NH3 throughout the water column and the release of gaseous NH3 and H2S to the air. The effect of this could be an annual die off of most fish in the Sea and serious odor problems. There are also potential human health impacts, including headache and nausea, as well as more serious problems for sensitive individuals.

Responses to Comments on Draft Summary Report

Reclamation has incorporated comments received on the January 31, 2007, draft of this Summary Report. Where appropriate changes have been made to this report as a result of these comments. Attachment B contains the comments that were received, as well as Reclamation’s responses. The responses to comments are indexed according to numbers assigned to each specific comment as depicted on the letters from each agency or individual. The numbers were assigned by Reclamation.

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Chapter 2. History of Plan Formulation This present study to attempt to determine a reasonable alternative concept for restoring the Salton Sea uses information from both recent (1998–2005) and past (1960s to 2003) studies. The specific concepts evaluated in this present study were screened and selected from hundreds of ideas and concepts that ranged from circulating ocean water from the Gulf of California or the Pacific Ocean to removing salts at the Sea through the use of enormous desalination plants, solar pond systems and/or enhanced evaporation systems.

Rising salinity concentrations and the realization in the 1960s that increased salinity levels would eventually affect uses at the Sea led to various study efforts to determine methods to manage salinity. Early efforts and investigations to determine methods to reduce salinity in the Sea began in 1965 and resulted in the preparation of a 1969 Federal/State Reconnaissance Investigation Report and the 1974 Salton Sea Project Feasibility Report (Reclamation and State of California, 1974). Although numerous concepts for reducing salinity were studied and reported, rising water surface elevations at the Sea, due to increased agricultural development and subsequent drainage inflows into the Sea, muted the need for project implementation at that time.

In the mid-1980s, Federal and State agencies again began looking into ways of controlling salinity. P.L. 102-575, passed in 1992, gave Reclamation the authority to conduct salinity control studies. In response to that law, Reclamation and the Salton Sea Authority (SSA), which was established in 1993, published and provided a report to Congress in 1997 that contained an evaluation of a wide suite of proposed alternatives intended to address the salinity and elevation problems of the Sea.

In 1996, an initial screening study was conducted through an agreement with the SSA, the California Department of Water Resources (DWR), and Reclamation. In an effort to include a wide variety of potential solutions to the problems of the Sea, media announcements and public meetings were used to invite submittals of restoration alternatives. Through these efforts, 54 alternatives were identified and evaluated through a preliminary technical screening process. This preliminary screening effort provided the framework for developing alternatives in 1998 that would be analyzed and documented by various efforts, including a cooperative federal and state National Environmental Policy Act and California Environmental Quality Act (NEPA/CEQA) initiative.

Subsequent to the passage of the Salton Sea Reclamation Act of 1998, Reclamation and the SSA began the process of developing a Draft Environmental Impact Statement/Environmental Impact Report (DEIS/EIR). As part of this NEPA/CEQA process, required public scoping meetings resulted in further


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alternative suggestions, as well as comments concerning the 54 alternatives that were derived from the previously mentioned screening process.

All 54 original alternatives were re-assessed, and new alternatives were considered, including those suggested by the public in 1998. The reassessment yielded 39 alternatives that were carried forward for additional screening analysis. A description of these alternatives is provided in the Salton Sea Alternatives Final Pre-Appraisal Report (November, 1998).

Subsequently, a January 2000 DEIS/EIR considered five project alternatives and compared each against three No Action/No-Project scenarios. Analysis of alternatives continued following publication of the DEIS/EIR and the receipt of public and agency comments. In addition, more information became available about the range of possible inflows to the Sea that could occur in the future. Restoration alternatives studies also continued following publication of the DEIS/EIR. In these studies, the strategy for salinity control presented in the DEIS/EIR was replaced by a strategy involving two basic types of modules for salinity control: salt removal modules and salt disposal modules. Using the modular strategy, eight salinity control alternatives, three salinity and elevation control alternatives, an alternative that would have involved construction on an impervious barrier across the middle of the Sea, and two specialized diking proposals were considered in a January 2003 status report (Reclamation, 2003).

After publication of the 2003 status report, the Quantification Settlement Agreement (QSA) was reached, and the associated Imperial Irrigation District (IID)/San Diego Transfer Agreement was approved. As a result of anticipated reduced inflows, alternatives involving salt removal and disposal were abandoned in favor of partial restoration solutions such as equal head barriers and impervious dam alternatives as well as habitat-pond-based alternative concepts. Reclamation’s current alternatives include only these types of alternatives. The current alternatives presented in this summary report are as follows:

• Mid-Sea Dam with North Marine Lake • Mid-Sea Barrier with South Marine Lake • Concentric Lakes • North-Sea Dam with Marine Lake • Habitat Enhancement without Marine Lake • No-Project

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Chapter 3. Restoration Alternatives This chapter describes the primary structural and physical features of each alternative, including the No Project Alternative. Included are descriptions of alternative-specific features, such as water quality treatment systems and innovative construction methods. This chapter also describes common features associated with alternatives, e.g., saline habitat complexes (SHC), associated early start projects, and air quality mitigation (AQM) projects. Lastly, this chapter describes embankment designs, design criteria, design considerations, and comparisons to Reclamation’s design criteria and guidelines for each of the action alternatives.

This report evaluates the following alternatives:

1. Mid-Sea Dam with North Marine Lake (proposed by the SSA)

2. Mid-Sea Barrier with South Marine Lake

3. Concentric Lakes (proposed by the Imperial Group)

4. North-Sea Dam with Marine Lake

5. Habitat Enhancement without Marine Lake

6. No-Project

Reclamation coordinated closely with the State of California DWR and the Salton Sea Authority in developing the alternatives presented in this report. Consequently, both the State and Reclamation have analyzed alternatives that are conceptually similar, yet have some differences. Variation between agencies in approaches to risk, uncertainty, complexity, and other factors contribute to differences in designs and costs. While Reclamation’s design and cost estimating criteria and guidelines may be different than those used by other agencies and this may lead to different design conclusions and project costs, Reclamation makes no judgment relative to methods, assumptions, and criteria used by others.

Reclamation recognizes that any site-specific evaluation and/or alternative implementation would require consultation with the U.S. Fish and Wildlife Service, the Torres Martinez Nation, and others to ensure consistency with other missions and land uses.

It was Reclamation’s intention to provide the highest quality design and cost estimates within the constraints of funding, schedule, and available information. Available knowledge of geologic conditions, in particular, was limited.

These factors should be taken into consideration when comparing costs of alternatives presented in this report to those presented in DWR’s Salton Sea


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Ecosystem Restoration Program draft programmatic environmental impact report (PEIR) and to reports prepared by other organizations.

The drains that flow directly into the Salton Sea are potential habitat for the desert pupfish. In the future, IID will provide for connectivity among the direct-to-sea drains in areas on the south end of the Salton Sea; this will be required as mitigation for the IID/San Diego water transfer project. These mitigation requirements are not directly reflected in any of the alternative depictions presented in this chapter. However, it is recognized that future implementation of any of these alternatives would need to address these mitigation actions.

Common Features

Alternative Nos. 1, 2, 4, and 5 include SHCs formed by earthen embankments. All alternatives include an early start for development of SHCs or habitat areas. All alternatives also include facilities for performing AQM. A discussion of these common features follows.

Saline Habitat Complexes About 20 percent of the total SHC would be deep open water (up to 10 feet) for fisheries. These deep-water pond areas would be constructed through excavation; the excavated material would be used to create islands behind cell embankments. The remaining portion of the SHC would be divided into areas suitable for different species and their use. The majority of these shallow-water pond habitats would be less than 3 feet deep; up to a quarter of these areas would be land. Figure 3.1 depicts a cell in a typical SHC.

Inflows to the SHCs would be managed to achieve an average salinity of more than 20,000 mg/L and less than 35,000 mg/L through the mixing of waters from the rivers and alternative-specific marine lakes or brine pools. Water would flow by gravity through each of the habitat complex cells. The salinity would increase in each cell until it reaches about 150,000 mg/L, whereby discharges from the last cell would be made to the brine pool specific to each alternative. The water is expected to have habitat value up to a salinity of about 150,000 mg/L.

The SSA has recently proposed a different set of assumptions for the SHC design in its alternative. The SSA has proposed not to include deep-water pond areas in

Saline habitat complex.

Chapter 3. Restoration Alternatives

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Figure 3.1 Cell in a typical SHC.

its SHC design. The SSA is also assuming that the SHC would be 50 percent water and 50 percent land. To ensure that all alternatives were evaluated and compared on an equal basis, Reclamation assumed the SSA alternative had the same type of SHC as the other alternatives, which includes deep water pond areas. Without deep holes for a fishery in the SHC, there would be no opportunity for an early start fishery under this alternative.

Early Start Projects For all alternatives, it was assumed that construction would be completed in the year 2024. Assumptions for project completion are discussed in Chapter 4. Prior to completion of project construction the Sea is expected to experience environmental degradation involving the complete loss of the fishery and the collapse of the invertebrate food base. In order to provide some replacement habitat, all alternatives were assumed to include early start SHC development features. These early start features would be designed to offset negative habitat impacts during the construction period and could be implemented in phases in 200 to 500-acre units. These units would be located in areas compatible with the SHC complex build out for each alternative and would likely be constructed in the south end of the Sea that would be exposed in the near future. Each phase would be constructed every 3 to 5 years.

The Concentric Lakes Alternative would also have an early start project and could involve the construction of small ring dike impounded areas that could be operated consistent with concentric lakes operation concepts as well as SHC operation concepts.


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Early start areas would need to be monitored and adaptively managed over time to develop procedures to mitigate Se, eutrophication, and fishery sustainability problems. These areas would also be studied for habitat values and uses by functional bird groups, such as fish-eating birds, divers, shorebirds, long-legged waders, etc.

Air Quality Mitigation Projects Each alternative (including No-Project) includes an AQM project for control of emissions from exposed playa areas. The AQM project for all of the alternatives adheres to the methods described in DWR’s Salton Sea Ecosystem Restoration Program Draft PEIR, Appendix H-3: “Identify and Outline Measures to Control Playa Emissions.” The California legislature enacted certain laws in 2003 providing for preparation of the Salton Sea ERS and PEIR that include specific air quality monitoring and mitigation steps to be taken. Under the California State Water Resources Control Board Order (SWRCB, 2002) and the IID Water Conservation and Transfer Project Mitigation, Monitoring, and Reporting Program (IID, 2003) potential air quality impacts from exposed Salton Sea playa must be monitored and mitigated. It is assumed the State of California will manage AQM in coordination with landowners and other stakeholders. For the No Project Alternative, AQM for the IID/San Diego water transfer project would be implemented by IID in coordination with California State regulating agencies.

The SSA has proposed use of salt crusting to eliminate most AQM requirements. SSA made this proposal under the premise that relatively pure halite (NaCL) crusts can be formed to eliminate the opportunity for playa emissions. The potential effectiveness of this approach has a high level of uncertainty. Research at the Salton Sea (Reclamation, 2004) indicates that the crusts that will be formed will predominantly be mixed-salts with continuous formation of a mixture of NaCL and bloedite (Na2Mg(SO4)24H2O). Based on these research observations, it is possible that sulfate salt transformations and associated crust friability could lead to airborne particulate emissions from the salt crust areas. As a result, the SSA proposal to use salt crusting as a means of AQM was not used in the evaluation of the SSA alternative. A cost estimate that assumed use of salt crusting for AQM was made of the SSA’s original alternative. These costs are presented for comparison purposes in Attachment A of this report.

The approach used by DWR in the PEIR (for most alternatives) assumes that 30 percent of the exposed area would not require active AQM. This approach also assumes that 50 percent of the exposed area would require AQM using water-efficient vegetation, and 20 percent of the exposed area would require AQM using other methods. This approach to AQM was applied to all alternatives studied by Reclamation.


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Table 4.1 in Chapter 4 lists exposed playa surface areas for each alternative and the acreages of each to be mitigated with water-efficient vegetation and non-water based control measures. These acreages were predicted using computer modeling, as described in Chapter 4.

Alternative No. 1: Mid-Sea Dam with North Marine Lake (SSA Alternative)

Alternative No. 1 was proposed by the SSA. It would provide both salinity and elevation control and up to 16,000 acres of SHC. Figure 3.2 presents the alternative under mean possible future inflow conditions (727,000 acre-feet per year) as described in Chapter 4. The mid-Sea embankment location of this alternative was originally proposed by the SSA to be located approximately 1.5 miles south of the position shown in Figure 3.2. The SSA proposed the new location to allow for enhanced capabilities to manage for future salinity concentrations in the north marine lake. Figure 3.2 and all analyses presented in the main body of this report are based on this new dam alignment. Table 3.1 lists physical features associated with Alternative No. 1 under mean future inflow conditions in the year 2040. All depictions of alternatives in this chapter are associated with year 2040. In this year, all alternatives are expected to reach (or nearly reach) equilibrium with respect to environmental conditions.

Alternative No. 1 (Figure 3.2) includes a total of four embankments: (1) an impervious mid-Sea dam, (2) an east-side perimeter dike, (3) a west-side perimeter dike, and (4) a south-Sea dam. These structures would be built using the sand dam with stone columns concept described later in this chapter. The embankment design would provide for both static and seismic risk reduction. Reclamation evaluated the rockfill embankment concept proposed by the SSA and determined that it would not meet Reclamation’s general design criteria. The embankments would be constructed so the water north of the mid-Sea dam would be maintained at a higher elevation than the brine pool on the south side. The area south of the mid-Sea dam would serve as an outlet for water and salt from the north and would rapidly shrink in size and increase in salinity to form a brine pool. In addition to the north marine lake, a smaller south marine lake would be created by the south-Sea dam. These

Original SSA Alternative: The SSA’s original alternative incorporated a mid-Sea dam about 1.5 miles farther south than what is presented in Figure 3.2. This alternative also included a smaller SHC of 12,000 acres. Cost estimates were prepared for the SSA’s original alternative. These estimates provide a basis for making comparisons to cost estimates prepared by DWR and the SSA for this same original alternative. Attachment A of this summary report contains these cost estimates assuming that embankments would be built using rockfill embankments similar to those being proposed by the SSA (Alternative 1B). The estimate presented in Attachment A assumes the use of salt crusting (as originally proposed by the SSA) via construction of small earth embankments (2.5 feet tall) to impound brine released from the SHC. Reclamation evaluated the rockfill embankment concept and determined it would not meet Reclamation’s general design criteria.


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Figure 3.2 Alternative No. 1: Mid-Sea Dam with North Marine Lake (SSA Alternative).

Table 3.1 Physical features of Alternative No. 1: Mid-Sea Dam with North Marine Lake

Physical Feature Value Marine lake surface area 98,900 acres Marine lake maximum depth 43.5 feet SHC surface area 16,000 acres Total open water habitat surface area 106,900 acres Total shoreline habitat surface area 26,600 acres Brine pool surface area 17,600 acres Exposed playa surface area 103,800 acres

Deep Sea Water Pipeline and Pumping Plant

Sea Water Treatment Plants

Perimeter Dike & Circulation Canal

Saline Habitat Complex

South-Sea Dam

Mid-Sea Dam

Perimeter Dike River Water Treatment Plants



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two bodies of water would be connected along the western edge of the Sea by the west-side perimeter dike and along the eastern edge by the east-side perimeter dike and canal. The north marine lake would have a mean future water surface elevation of about -238 feet msl under mean possible future inflows as described in Chapter 4. The estimated long-term elevation of the brine pool is about -272 feet msl. The alternative includes 16,000 acres of SHC and a dedicated habitat area on the north end of the Sea. It also includes a deep water pipeline, an ozonation treatment plant, a water circulation system, and a phosphorous removal treatment plant.

The conveyance features included in this alternative consist of a circulation canal, sludge conveyance pipeline, back-flush waste pipeline, three pumping plants, and two associated pipelines. These conveyance

features would be used to provide water to AQM projects, to handle discharge to and from treatment plants, and to circulate water. These features also would provide marine lake water to be mixed with river water delivered to the SHCs.

This alternative was not studied under the assumption of a guaranteed minimum water supply. The Salton Sea has no assured water supply in the future. Therefore, the alternative was studied using the risk-based approach to inflow described in Chapter 4. On the basis of this risk-based approach to inflows, it was necessary to adjust the operating elevation of the marine lake to -238 feet. Without this flexibility in the operating elevation of the lake, the salinity levels cannot be reduced sufficiently (by the year 2040) to maintain a fishery under mean possible future inflow conditions. The SSA has proposed an operating elevation in the marine lake of -230 feet. On the basis of the risk-based approach to future inflows, this may not be possible until after the year 2055 when the salinity in the marine lake is reduced to 45,000 mg/L, stabilized, and then only under certain higher possible inflow conditions. If future inflow conditions are above mean possible estimates, then the operating elevation of the marine lake could be higher and potentially at a level consistent with the SSA’s target if -230 feet. If future inflows are below mean possible future conditions, then the lake would have to be operated at elevations of less than -238 feet to maintain salinities at fishery-compatible levels.

Mean Possible Future Inflows: Without future assurances of inflows to the Salton Sea, there will be some degree of performance uncertainty (risk) for any Salton Sea restoration alternative. Under some scenarios, inflows to the Sea might be reduced to a level that puts the success of restoration in jeopardy. The impacts of the risks and uncertainties of inflows on each restoration alternative were assessed in this study. These assessments were made using advanced computer modeling techniques. Each alternative was modeled using a risk-based approach to inflows in which 10,000 different possible future Salton Sea inflows scenarios were simulated. The mean (or average) inflow computed from of all these possible futures is described as the “Mean Possible Future Inflow Condition” and would have a value of 727,000 acre-feet per year. The risk-based approach to inflows is described further in Chapter 4.


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Alternative No. 2: Mid-Sea Barrier with South Marine Lake

Alternative No. 2 would provide salinity control but no elevation control and up to 21,700 acres of SHC. Figure 3.3 presents the alternative under mean possible future inflow conditions (727,000 acre-feet per year). Table 3.2 lists physical features associated with Alternative No. 2 under mean future conditions in the year 2040.

The alternative includes a mid-Sea barrier designed to generally be operated with equal heads on both sides and to accommodate a differential head of up to 5 feet.

Figure 3.3 Alternative No. 2: Mid-Sea Barrier with South Marine Lake.


Equal Head Mid-Sea Barrier


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Table 3.2 Physical features of Alternative No. 2: Mid-Sea Barrier with South Marine Lake

Physical Feature Value Marine lake surface area 59,700 acres Marine lake maximum depth 15.5 feet SHC surface area 21,700 acres Total open water habitat surface area 49,000 acres Total shoreline habitat surface area 34,700 acres Brine pool surface area 66,000 acres Exposed playa surface area 73,600 acres

The water entering the Sea from the south into the south marine lake would support a large marine habitat. The estimated long-term elevation of the marine lake and brine pool under mean future conditions is -261 feet msl. The majority of inflows are expected to occur from the south end; therefore, the area north of the barrier embankment is expected to serve as an outlet for water and salt from the south side. The north side would quickly form a brine pool. As the main body of the Sea shrinks, embankments would be constructed to create SHC. The mid-Sea barrier would be constructed with a crest elevation of -245 feet and would accommodate the forecasted reductions in inflows when mitigation water is terminated under the IID/San Diego Transfer Agreement.

The 21,700 acres of SHC would be constructed on the southeast and north ends of the Salton Sea.

The conveyance features included in this alternative consist of five diversion crests and sediment detention basins, four pupfish/river water channels, five

restoration of the salton sea - six silberman · coordination with the state of california and the...

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